In which of the following, the work done by the mentioned force is negative ? The work done by

In which of the following cases no work is done by the force?

In which of the following cases no work is done by the force?

In which of the following cases is the work done positive or zero or negative ? Work done by force of gravity on a ball thrown up vertically up into the sky.

In which of the following cases is the work done positive or zero or negative ? Work done by the force of gravity on suitcase as the suitcase falls from porter's head.

In which of the following cases is the work done positive or zero or negative ? Work done by the porter on a suitcase in lifting it from the platform on to his head.

Work done by a frictional force is

Work done by a frictional force is